A glovebox (also known as an inert atmosphere box or containment box) is a hermetically sealed container that is designed to allow one to manipulate objects where a separate inert atmosphere is desired. A typical glovebox 1 is shown in FIG. 1. Built into a side of the glovebox are gloves 2 typically made of an elastic material, arranged in such a way that the user can place their hands into the gloves and perform tasks inside the box without breaking the seal of the container. At least part of the glovebox is transparent to allow the user to see what is being manipulated. A glovebox allows a user to work with substances that must be contained within a very high purity inert atmosphere, such as argon or nitrogen. The inert atmosphere within a glovebox typically needs to be maintained at less than 1 part per million (ppm) moisture, and/or to less than 1 ppm oxygen. To maintain such a low level of moisture, and/or oxygen in the inert atmosphere, media (also referred to herein for convenience as “media”, “filtering media” or “removal media”) is installed external to the glovebox and inert gas from within the glovebox is circulated through such media. For moisture removal the media used is typically molecular sieves, activated alumina or silica gels and moisture is removed by adsorption. For oxygen removal the media is typically a high surface area substrate with a thin layer of surface copper that removes oxygen by the oxidation of the surface copper. The media are housed in a structure, such as a vessel 3, external to the box and conduits 4 are connected to the interior of the box for providing flow of inert gas from the glovebox through the media and back to the glovebox. Moisture removal media and the oxygen removal media may be housed in separate structures or vessels; although more typically they are housed, in layers, in one structure. In either case, the inert gas from the interior of the glovebox is circulated through media containing structure or structures. Examples of gloveboxes are the VAC 101965 OMNI-LAB Glovebox System and the VAC 105320 NEXUS-II Glovebox System available from Vacuum Atmospheres Company. Objects to be worked in the glovebox are placed in the glovebox through an antechamber 5. With time, moisture and oxygen levels in the glovebox increase as the outside atmosphere may permeate through the gloves or enter the glovebox when materials and objects are brought into or removed from the glovebox through the antechamber. The glovebox inert atmosphere is caused to continuously flow from the glovebox through the media and returned to the glovebox for reducing and/or maintaining the inert gas atmosphere moisture and oxygen levels to desirable levels, as for example less than 1 ppm moisture and/or less than 1 ppm oxygen. The glovebox inert gas atmosphere is caused to flow through the media either by a fan assembly located within the glovebox with an outlet port of the fan assembly connected to the conduit 4 connected to the inlet of the vessel containing the media or by a hermetically sealed fan assembly located externally at or near the media vessel 3.
Eventually, the moisture and oxygen removal media in vessel 3 gradually approach their maximum removal capacities and their removal efficiencies decrease until they cannot maintain the desired moisture and/or oxygen level. At that point the removal media needs to be “regenerated.” In a typical glovebox system regeneration of the moisture removal media and the oxygen removal media are generally performed at the same time. To accomplish this, flow from the glovebox through the media is stopped. The vessel with the removal media is isolated from the glovebox by closing valves in the conduits connecting the vessel with the glovebox. The vessel containing the oxygen removal media and the moisture removal media is then heated to approximately 200° C. This process takes several hours. Once the desired temperature is reached, an inert gas from a supply tank is connected to the media vessel in a manner that causes flow in the reverse direction to the flow from glovebox inert gas. After the inert regeneration gas passes through the media the gas is vented to the outside or room atmosphere. This regeneration gas purge step typically takes one hour. If the media is for moisture removal, an inert gas with less than 20 ppm moisture is required. If the media is for oxygen removal or both moisture and oxygen removal the inert gas used for regeneration contains 1%-3% hydrogen. Following the purge with the regeneration gas the media is allowed to cool. After cool down, the vessel and removal media are placed under vacuum for several hours. The removal media vessel is then refilled with inert gas to the same pressure as the pressure as that of the glovebox. The isolation valves are then opened and flow of inert gas from the glovebox is reestablished and removal of moisture and/or oxygen from the inert gas may begin.
For a typical glovebox this regeneration process requires 12 to 24 hours. For units with a single vessel of removal media, the glovebox will be out of service for that period of time. If the glovebox has two removal vessels, when the vessel containing the exhausted media is taken off line for regeneration the other vessel, previously regenerated, is placed on-line and will remain on-line until it becomes exhausted and the initial vessel with regenerated media is placed on line.